THE CRINOIDEA 139 



and the supposed absence of an anus ; but no group name was proposed. 

 All other crinoids then known were placed in the TESSELLATA, which 

 included the unstalked Marsupites ; their cup was said to be composed 

 entirely of plates, to which names were given (BB, RR, Ax, etc.), and 

 their tegmen was said to be solid, with only one opening, and with no 

 food-grooves. This classification, while retaining as a guide the mode of 

 union of the plates, took also into consideration the structure of the tegmen. 



Zittel (1879) divided the Crinoidea brachiata, EUCRINOIDEA, as he 

 called them, into three sub-orders, on the basis of Miiller's classification, 

 but merging Hotyms and the Testacea in the Articulata. TESSELATA : 

 cup-plates thin, immovably united by simple suture ; tegmen solidly 

 plated ; mouth subtegminal ; Marsupites, Uintacrinus, and all Palaeozoic 

 crinoids. ARTICULATA : cup-plates usually very thick, united by articu- 

 lating or plane sutures ; tegrnen integumentary, rarely plated, with open 

 food-grooves and central mouth ; all Neozoic forms, except those here 

 mentioned under other sub-orders. COSTATA : Saccocoma (see under 

 Miiller). By this time several families had been founded, notably by 

 C. F. Roemer (1855) and Angelin (1878). These were added to by 

 Zittel, and those of the Tesselata arranged in groups, chiefly according 

 to the construction of the tegmen. Most of the families were well 

 founded, but the characters of the Tesselata and Articulata, though 

 applicable to a few genera, were not really capable of extension to all the 

 forms that had become known since the time of Miiller. 



Wachsmuth's establishment of the PALAEOCRIXOIDEA in 1877, "to 

 include those forms in which the disc is roofed by a second integument, 

 which he supposed to exist in all Palaeozoic crinoids" (W. & Sp.), 

 has already been noticed. The order covered nearly the same ground 

 as the Tessellata, and opposed to it was the order Stomatocrinoidea 

 or NEOCRINOIDEA, corresponding roughly to the Articulata. Carpenter 

 & Etheridge (1881) accepted the division, but laid more stress on the 

 asymmetry of the posterior interradius in Palaeocrinoidea, and therefore 

 suggested IRREGULARIA and REGULARIA. 



Wachsmuth & Springer (1885) divided their Palaeocrinoidea into 

 three sub-orders, originally suggested by Wachsmuth's study of the tegmen. 

 CA.MERATA : tegmen rigid, formed of rather large thick plates ; brachia 

 in part rigidly incorporated in cup by means of interbrachials ; Reteo- 

 crinidae, Rhodocrinidae, Thysanocrinidae, Glyptasteridae, Melocrinidae, 

 Actinocrinidae, Platycrinidae, Hexacrinidae, Eucalyptocrinidae, Barrandeo- 

 crinidae, and Acrocrinidae. ARTICULATA : tegmen flexible, formed of 

 minute plates ; brachia may or may not be partly incorporated in cup, 

 but not rigidly ; Ichthyocrinidae, Crotalocrinidae. 1 INADUNATA : brachia 

 not incorporated in cup. These were divided into LARVIFORMIA : 

 tegmen of few plates; "disc" covered by "vault"; Haplocrinidae. 

 Cupressocrinidae, Gasterocomidae, 2 Stephanocrinidae ; and FISTULATA : 

 "disc "not entirely covered by "vault," but passes out as a porous 

 " ventral sac " ; Hybocrinidae, Heterocrinidae, Anomalocrinidae, Belemno- 

 crinidae, Cyathocrinidae, Calceocrinidae, Catillocrinidae, Poteriocrinidae, 

 Encrinidae, Astylocrinidae. 



1 Removed to Camerata in 1888. 2 Removed to Fistulata in 1890. 



